Report on the lands of the arid region of the United States, with a more detailed account of the lands of Utah

by John Wesley Powell; Willis Drummond; Clarence E. Dutton; Grove Karl Gilbert; A. H. Thompson

In the San Pete Valley, which has been cultivated as far up as Mount Pleasant for twenty years, I cannot learn that any crop has ever been injured by frosts, and we may therefore conclude that this valley is safe from such an attack, unless a most abnormal one. The same may be said of the main Sevier Valley from Joseph City downward. From Joseph City to Circle Valley there is a relatively small proportion of irrigable land, but such as there is may, I think, be regarded as safe from frost. Circle Valley, where the two forks unite, has been cultivated for cereals for four years, and has not yet suffered from frost, and it is fair to assume that such a calamity will be very infrequent there, though it may not be possible to say there is no danger. In Panguitch Valley, a severe frost in August, 1874, inflicted great injury upon the crops, and only a small quantity of very inferior grain was harvested. But in 1875, 1876, and 1877, excellent crops were secured. Above Panguitch the amount of arable land is not great, and the danger to crops is increased. In Grass Valley there is a magnificent expanse of fertile arable land, but there can be no question that a large portion of it is so liable to killing frosts in August, or even in July, that the cereals cannot flourish there. The lower portion of the valley, near the head of East Fork Cañon, is more hopeful, and it is probable that a large majority of crops planted there will mature, though occasional damage may be reasonably looked for. The general result may be summarized as follows: Below 6,000 feet crops may be considered as safe from serious damage by frosts. From 6,000 to 7,000 feet crops are liable to damage in a degree proportional to the excess of altitude above 6,000 feet. Above 7,000 feet the danger is probably such as to render agriculture of little value to those who may pursue it.

The climate has shown in past times a longer period of variation than the annual one. Panguitch was settled once in 1860, but was abandoned on account of the destruction of crops by the frosts. The settlement was renewed in 1867, and again abandoned, in consequence of the attacks of Indians. It was settled a third time in 1870, and, though crops have occasionally been injured, the agriculture has on the whole proved remunerative.

Let us now look at the irrigable lands of the Sevier and its tributaries. Above the town of Panguitch, on the South Fork, there is a considerable area of arable land, which could be easily reached by canals from the main stream and below 7,000 feet altitude, but for want of a detailed survey it is impossible to do more than guess at the area. I think, however, that 8,000 acres would be the maximum limit. This portion of the valley is liable to killing frosts, though during the last three years it has not suffered from this cause. In the long run, I believe agriculture will not prove remunerative here. From Panguitch northward to the head of the Panguitch Cañon, a distance of 18 miles, is a broad valley, averaging 5 miles in width, a very large portion of which is irrigable, provided the water supply is adequate. At least 24,000 acres may be cultivated without resort to anything more than the usual methods of distributing the water; but not the whole of this area is fertile. The greater part of the area of Panguitch Valley is composed of alluvial slopes, or, as they have been termed by geologists, alluvial cones. Although these surface features are presented in a somewhat more typical and striking manner in Grass Valley, yet they are well enough exhibited here; and as they have an important relation to the subject, I will briefly discuss them.

In a mountainous country like this, where the melting of the snows in spring or heavy rainfalls at other seasons create sudden and great torrents, large quantities of detritus are carried down from the mountains into the valleys. These mountain streams, which in summer, autumn, and early winter are ordinarily either very small or wholly dried up, may upon certain occasions become devastating floods. The bottoms of the ravines are steep water courses, down which the angry torrents rush with a power which is seldom comprehended by those who dwell in less rugged regions. Huge boulders weighing several tons, great trees, with smaller débris of rocks, gravel, sand, and clay, are swept along with resistless force, until the decreasing slope diminishes the energy sufficiently to permit the greater boulders to come to rest, while the smaller ones are still swept onward. The decrease of slope is continuous, so that smaller and smaller fragments reach a stable position, and only cobblestones, gravel, or sand reach the junctions of the streams with the main rivers. Around the openings of the greater gorges and ravines the deposits of coarser detritus build up in the lapse of time the alluvial cones. As it accumulates, each torrent builds up its bed and constantly changes the position of its channel, and with the mouth of the ravine for a center it sweeps around from right to left and left to right like a radius, adding continually, year after year, to the accumulations of detritus. Thus a portion of a flat cone is formed, having its apex at the mouth of the ravine. At the foot of mountain ranges these alluvial cones are formed at the mouth of every ravine, and are sometimes so near together that they intersect each other, or become confluent. They are composed of rudely stratified materials, ranging in size or grain from fine silt and sand to rounded stones of several hundredweight, and occasionally a block of a ton or more may be seen near the apex of the cone. In regions where the rocks are soft and readily disintegrated the stones are more worn, less in number, and smaller in size, and this is the case generally with unaltered sedimentary rocks. But in valleys running among volcanic ranges, the much greater hardness and durability of the materials preserve them from disintegration, and the stones are more numerous, larger, and less worn by attrition, composing indeed a very large proportion of the bulk of the alluvial cones. A large portion of the valley of the Sevier lies in the midst of a volcanic region, and its sides are everywhere flanked with these alluvial cones, which are very stony and gravelly. The lower portion of the Sevier is in a country made of sedimentary beds, and though the alluvial cones are equally common, they consist of finer material, and are less burdened with stones.

The Panguitch Valley is between volcanic plateaus, and most of its area consists of alluvial cone land, which is no doubt fertile wherever the stones and rubble are not sufficient to prevent plowing and planting, but this difficulty must render it at least very undesirable. There is, however, a large area of land of another description in Panguitch Valley, composed of the finest silt brought down by the gentler current of the river itself, and deposited within its own basin. This is good bottom land, and the amount of it I estimate at not less than 7,000 acres. It has already been remarked that Panguitch Valley stands at an altitude above 6,000 feet, and is not free from danger of summer frosts. These have been known to destroy or seriously injure the grain, though in a majority of years crops will no doubt be safely harvested. Whether the danger is such as to make agriculture unremunerative in the long run experience can alone demonstrate.

Following the South Fork of the Sevier downward through the Panguitch cañons, the next important agricultural area is Circle Valley. This is a broad, nearly circular area, situated in the midst of scenery of the most magnificent description. Upon the east and west sides rise those gigantic cliffs which are the peculiar feature of the scenery of this elevated region, looking down upon the valley below from altitudes of 4,000 to 5,000 feet. This valley also has upon its sides long sloping areas of stony alluvial cones, full of blocks of trachyte and basalt washed down from the cliffs above. It has also a large area of arable land. There is in addition, a certain area of sandy land of an inferior degree of excellence. The area of best bottom land will probably reach as high as 6,000 acres. In this area there is probably very little danger from early frosts, as the 6,000 feet contour passes through the middle of the valley, and, as already stated, the areas which lie within this limit are reasonably safe from this occurrence. At the north end of Circle Valley we find the junction of the two main forks of the Sevier River. From the junction the main stream runs northward for nearly 20 miles, and throughout this entire stretch there is but little arable land. Upon both sides of the river there are long alluvial slopes, made up of stony materials and coarse gravels, through which a plow could scarcely be driven. A portion of the way the river runs between rocks and low cliffs and in abrupt cañons, cutting through old trachyte and basaltic outflows. Reaching Marysvale, we find a sufficient area for three or four good sized farms, consisting of bottom land of the finest quality, which can be watered either from the Sevier River itself or from two considerable affluents which come roaring down out of the Beaver Mountains. North of Marysvale is a barrier thrown across the valley, consisting of rugged hills of rhyolitic rocks, through which the river has cut a deep cañon; but agriculture in any portion of this barrier is out of the question. The river emerges from it at the head of what may be called its main or lower valley, near the Mormon settlement called Joseph City. From this point northward we find what must undoubtedly become the great agricultural area of southern Utah. It is a magnificent valley, nowhere less than 5 miles in width, and at least 60 miles in length, with abrupt mountain walls on either side, and almost the whole of its soil consisting of alluvial cones, and susceptible of a high degree of cultivation. The limit of the amount of land in this valley which can be irrigated is measured by the quantity of water which can be found to turn upon it. The western side of the valley is flanked by abrupt walls of sedimentary rocks. As I have before stated, the alluvial cones which find their origin in the degradation of these sedimentary walls are invariably composed of finer materials than those which come from the breaking up of volcanic rocks. The soil, therefore, is much more readily plowed and planted than the corresponding cones farther up the river. The surface of these cones, moreover, is coated with a thick layer of fine loam, and it is not until penetrated to a considerable depth that we come upon a coarser material. This portion of the valley of the Sevier has been under cultivation for more than eight years. The art of irrigation has also reached a certain stage of advancement, at which it can be studied with some interest. A canal of sufficient magnitude to carry the entire body of the water of the Sevier during the dry season has been run for a distance of 8 miles, and is used for irrigating the large grain fields which lie around Richfield; and, as irrigation is now conducted, the entire flow of the stream is turned through this canal after having been employed for irrigating the various fields, which extend for the distance of nearly 7 miles. The total amount of irrigable land which may be found between Joseph City on the south and the point where the Sevier leaves its proper valley, 65 miles to the northward, cannot be much less than 90,000 acres. The limit of irrigation throughout this entire valley is the limit of the water supply.

There is one other valley to which we must advert, namely, the valley of the San Pete. This is fully equal in fertility and in the convenience of every element connected with irrigation to the best part of the main valley of the Sevier. The San Pete is a stream of considerable magnitude, and experience has shown that it is probably capable, under a more improved system of irrigation than that now in use, of watering the greater portion of its valley. The cultivable acreage of the San Pete Valley is about 55,000 acres, provided the whole could be watered.

The quantity of water carried by the Sevier will now be considered. This, of course, is highly variable from month to month. The time for measurement, if the true irrigating capacity of the stream is to be considered, should be that time at which the ratio of water in the stream to the amount required is smallest. At different stages of growth of the crops the amount of water required differs considerably. The largest amount is needed about the time the seeds of the grain begin to fill out. Ordinarily this is in the latter part of July and early in August throughout the lower and most extensive portion of the valley, and a week later in the upper portions. At this season the water is not at its minimum. There is a gradual diminution of the flow during July, but the great shrinkage of the stream occurs during the middle of August, just after, or sometimes even during, those irrigations in which the greatest amount is required. The critical period of the crops occurs, therefore, just before, and sometimes dangerously near, the period of rapid decline in the water supply. It will therefore be evident that it is not a very easy matter to determine the exact stage of water which can serve as a criterion of the irrigating capacity. My own measurements, however, were hardly a matter of choice, but were made at the most advantageous period which could be selected without interfering with the primary objects of the expedition.

The Sevier was measured at the junction of the two main forks, at the north end of Circle Valley, on the 6th and 7th of July. The method adopted was first to find a section of the water at a given point by soundings and by actual measurement of the width of the water surfaces, and measuring the surface velocity by means of floats. The most probable mean result of several measurements was found to be 410 cubic feet per second for the East Fork, and 450 feet per second for the South Fork, or a total of 860 feet.

While this measurement was made the South Fork was being drawn upon above for the watering of about 1,100 acres near Panguitch, 35 miles farther up the stream, and also for watering about 600 acres in Circle Valley, about 3 to 4 miles above. The amount of water used in Circle Valley was probably greater than that at Panguitch, since the method employed was much more wasteful, and no provision made for returning the tail water to the stream. On the other hand, a large proportion of the tail water from both places finds its way back to the channel in spite of waste, but how much it is impossible to conjecture. I think, however, that 75 cubic feet per second would cover the loss from these sources.